Today's $500 Gaming PC

Link to Each Part: http://pcpartpicker.com/p/2KQhF

CPU: AMD Phenom II X4 945 3.0GHz Quad-Core Processor  ($80.98 @ SuperBiiz)
Motherboard: Gigabyte GA-78LMT-USB3 Micro ATX AM3+ Motherboard  ($49.99 @ Microcenter)
Memory: Crucial Ballistix Sport 8GB (1 x 8GB) DDR3-1600 Memory  ($66.99 @ Microcenter)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($59.66 @ OutletPC)
Video Card: XFX Radeon HD 7770 GHz Edition 1GB Video Card  ($89.99 @ NCIX US)
Case: Cougar Solution (Black) ATX Mid Tower Case  ($29.99 @ Newegg)
Power Supply: Corsair Builder 430W 80+ Bronze Certified ATX Power Supply  ($19.99 @ Microcenter)
Optical Drive: LG GH24NSB0 DVD/CD Writer  ($14.99 @ Newegg)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit)  ($89.98 @ OutletPC)
Total: $502.56
(Prices include shipping, taxes, and discounts when available.)

Here is an Intel Build.

CPU: Intel Core i3-2120 3.3GHz Dual-Core Processor  ($103.98 @ SuperBiiz)
Motherboard: Gigabyte GA-H61M-S1 Micro ATX LGA1155 Motherboard  ($37.99 @ Newegg)
Memory: Crucial Ballistix Sport 8GB (1 x 8GB) DDR3-1600 Memory  ($66.99 @ Microcenter)
Storage: Western Digital Caviar Blue 1TB 3.5" 7200RPM Internal Hard Drive  ($59.66 @ OutletPC)
Video Card: Asus Radeon HD 7770 GHz Edition 1GB Video Card  ($87.99 @ Newegg)
Case: Cougar Solution (Black) ATX Mid Tower Case  ($29.99 @ Newegg)
Power Supply: Corsair Builder 430W 80+ Bronze Certified ATX Power Supply  ($19.99 @ Microcenter)
Optical Drive: LG GH24NSB0 DVD/CD Writer  ($15.99 @ Microcenter)
Operating System: Microsoft Windows 7 Home Premium SP1 (OEM) (64-bit)  ($91.48 @ OutletPC)
Total: $514.06